Burglar alarm



H H DUNN BURGLAR ALARM F l d J 1y 1 1925 Patented Apr. 13', 1926.

UNITED STATES PATENT OFFICE;

HERBERT H. DUNN, 0F PASADENA, CALIFORNIA, ASSIGNOR 0F LIAM VIGKERS, 0F PASADENA, CALIFORNIA.

ONE-HALF T0 wrL- BURGLAR ALARM. 2

Application filed uly 1,

which the following is a specification.

My invention is a burglar alarm adapted to be attached to a door, window or other opening and to explode the cap or similar explosive on the unautfhorized opening of the door or window.

My invention comprises a cap or explosive holder having a base with a slot therethrough for the flames from the explosive and comprises an anvil having a pin to which explosive caps may be attached and a stiff resilient leaf spring attached to the holder and positioned to be moved by the door or window when open. The explosive holder is positioned on the door or window frame and is secured thereto preferably by a thumb nut which may be loosened to allow the device to swivel downwardly by gravity to an inoperative position.

My invention will be more readily understood from the following description and drawings in which Figure 1 is a perspective view of a door with my burglar alarm attached thereto, showing the explosive holder positioned with the spring operating in a horizontal direction.

Fig. 2 is a perspective view of a window with the burglar alarm attached to the side frame and showing a pin attached to the sash to operate the spring in a vertical direction.

Fig. 3 is a side elevation of the alarm showing its position as if attached to a window.

Fig. 4 is a plan view of Fig. 3 in the direction of the arrow 1-. V

Fig. 5 is a perspective view of the explosive holder and the supporting swivel pins illustrating the manner of positioning the device to operate horizontally or vertically.

Fig. 6 is a perspective view of the type of cap suitable for my burglar alarm.

Referring particularly to Figs. 3 to 5, the explosive holder 1 comprises a metal arm having an opening 2 in its outer end with a small anvil block 3 inserted in the end, the inner end 4 is provided with a vertical and a horizontal aperture 5 and 6 to engage a 1925, Serial No. 40,873.

bolt 7 fastened'to a bracket 8, which latter has apertures 9 to allow fastening to a door or window frame. The thumb nut 10 is utilized to screw on the end of the bolt and thus clamp the device to the bracket.

The explosive holder would be mounted on a window by passing the bolt through the horizontal aperture 6 as shown in' Figs. 3 and 4 and by the full line bracket of Fig. 5. If the device is to be attached to a door the bolt will be inserted through the vertical aperture 5 to hold the explosivedevice in a horizontal position.

Thecap asshown in Fig. 6 is of the usual type having an explosive 11 mounted between two, paper fabric strips 12 which are sufficiently long between the packings of explosives to have depending skirts 13 or ends loosely hanging from the explosive center.

'A pin 14: sharpened at both ends is rigidly held in the anvil and extends slightly on both sides so that the paper or fabric on each side of the explosive may be pierced I and thereby hold the explosive of the cap positioned directly on the anvil.

The explosive hammer is formed by a resilient leaf spring 15 having its inner end secured by a screw 16 to the body of the explosive holder, preferably somewhat adjacent the bracket 8. The central portion 17 of the spring rests on the anvil and when charged on the exposed surface of the cap the free end 18 of the spring extending considerably beyond the explosive holder.

If the device is used on a window as above described the bracket 8 is attached to one of the side frames and the bolt 7 extends through the horizontal aperture 6. The device is then tightly clamped by the thumb nut 10 in a horizontal position so that the trigger pin 19 attached to the sash will ongage the spring when the sash is raised and thus force the spring upwardly until the end 18 slips off the pin, when the resiliency of the spring will snap it back into position explodmg the cap.

When the device is attached to a door as above mentioned the bolt 7 will extend through the aperture 5 and the device be clamped into position so that the spring will bend horizontally when engaged by the edge of the door in being opened. In this case the cap is inserted as above described being retained in position by the pins 14. As the door is opened the spring is bent backward iii) towards the person opening the door or,

window.

During the daytime or when it is not desired to set the alarm the thumb screw 10.

may be slightly loosened and the holder will swing into a vertical position by gravity and thus allow the opening of the door or window.

My burglar alarm is designed not only to frighten a burglar who may open the door or window but also to awaken the occupants of the house and to attract a police officer if in the neighborhood.

lVhile my device is of a simple character it may be considerably modified to suit different constructions of doors, windows or the like and may be built into the construction of the building instead of being an attachment. Moreover, various types of explosive caps could be used but I find the standard type above described held 'by the pointed pin let as quite satisfactory and inexpensive.

Having described my invention, what I claim is:

A burglar alarm, comprising in combination a bracket having a bolt, an explosive holder in the form of an elongated bar having an aperture therethrough at its inner end to receive the bolt, a thumb nut on the bolt to clamp the holder, an anvil on the outer end of the holder adapted to support an explosive cap, a resilient leaf spring attached to the inner end of the holder and having a section normally bearing on the anvil and a free end adapted to engage a movable object to flex and release the spring.

In testimony whereof I have signed myname to this specification.

HERBERT H. DUNN. 

